Facts

Streams

All that rain in Auckland ends up in the sea. Some takes centuries to get through groundwater and some evaporates. Most runs downhill removing soil and rock and forming small valleys with low ridges. In Auckland it is a short journey to the sea, so streams are small and in a dense pattern like the veins of a leaf. In their natural state they are great habitat for our iconic native fish who love little shady streams, close to richly productive estuaries like the Tamaki, Wairoa, Henderson Creek, and Mahurangi - all river valleys drowned at the end of the last Ice Age - where juveniles can feast.

There once were many swamps,formed when over forty-nine volcanoes spewed scoria and lava across the region with reckless disregard for the pattern of drainage.

This drainage pattern is now difficult to see. Queen Street in the Auckland central business district, for example, was once the channel of the Waihorotiu, now flowing underground in dark pipes. Creeks are tidal streams and were once deep enough for coastal scows (boats) to anchor. The name ‘creek’ is often applied to a whole watercourse as in ‘Otara Creek’. ‘Drains’ and ‘ditches’ are streams re-channelled for the convenience of landowners; ‘waterway’ and ‘watercourse’ are handy terms for any water from overland flow to estuary.

Bugs

Macroinvertebrates (or bugs) are an important aspect of stream health and some are more sensitive than others to pollution and degradation of stream health.

These bugs can be seen without a microscope. Many are the larvae or juvenile stages of flying insects such as dragonflies, mayflies, sandflies, and craneflies.

A healthy stream will have clear, flowing, cool water, with various pools, riffles, and runs. The riparian margins (stream edges) will be covered in native bush, providing shade, food and places for bugs (and other stream creatures) to hide.

Each type of bug has a particular sensitivity to factors such as chemical pollutants, sediment, increased water temperature, decreased dissolved oxygen and increased nutrient levels.

Freshwater Fish

New Zealand has a sparse but unique freshwater fish fauna. There are about 39 species, many of which are only found in this country (endemic). In addition to our native fish, several other species of fish have been introduced to New Zealand, including trout and salmon, and fish like perch, catfish and goldfish. Some introduced species are considered to be a nuisance because they have negative impacts on the environment or the native fauna. For example Gambusia (mosquito fish) outcompete native fish for food and habitat.

Monitoring

Wai Care groups do not generally actively monitor for fish populations because fish can be damaged during capture. The following links will help you identify a fish if you happen to catch one while sampling for macroinvertebrates.

Issues

New Zealand’s freshwater fish species are at risk of population decline and in some cases, extinction.

Here are a few reasons why:

Streams being directed into pipes or being impacted by hydro dams. This changes the habitat available for fish, giving them less food and places to hide.

Pollution entering the stream from roadside drains or careless polluters.